You can get a complete description of my History Probes at the link above, but basically, they allow you to see a history of values that have passed through a wire. I created History Probes for all scalar numeric datatypes (excluding U64 and I64, since I wrote these in LabVIEW 7.0), as well as strings, paths, and Booleans. These really helped me when debugging situations where I had a For Loop that ran a certain number of times, and I needed to see the sequence of values that passed through certain wires during each iteration of the loop. I hope other LabVIEW developers find these useful.

Re: Darren's Weekly Nugget 10/23/2006

The only limit is the maximum size of a 1D array, which is about 2 billion. But I imagine your system would bog down way before then. That's what the "Reset on Next Run" button is for...it clears out the history you've acquired up to that point and starts over.

Re: Darren's Weekly Nugget 10/23/2006

I've created similar probes, but I like the look of yours better (I didn't use a table, just a normat array indicator). I also added a "stats" tab that shows min, max, average and median and a conditional tab with lots of options to pause execution. I think I also have some that keep the timestamp of each value and provide an option to save to a tab-delimited file. I don't have a full set (never seem to use EXT or I8 I find that custom probes are one of the great unused features in LabVIEW. Why not throw in a bunch of historical probes for the next release?

Re: Darren's Weekly Nugget 10/23/2006

Thanks for the feedback...we'd have to do a bit of work to ship these History Probes with LabVIEW. For one thing, I was using them the other day to debug a race condition, and discovered they were quite slow (so slow, in fact, that simply using the History Probes eliminated the race condition)...this is probably because of the thread switching associated with frequent calls to the listbox property node to update the probe display. I prototyped a similar History Probe using the array control, but with a vertical scrollbar (new feature in LabVIEW 8.0, I think I mentioned it as a nugget earlier this year)...anyway, the array History Probe was much faster, since there were no Property Node calls. Nevertheless, I do recognize that these would be good to ship with the product, and I also agree that Custom Probes are one of the coolest features that came out in LabVIEW 7.0 (*almost* as cool as right-clicking a loop tunnel and choosing "Replace with Shift Register").